Write To a File Without Deleting

[SamGray]

Ok...so I'm trying to write a simple program to write the letter "a" into a text file. The problem is, is that when I already have things written in the text file, and run the program, it deletes all the other stuff in the file, and puts "a"...I have no idea how I can put the letter "a" after all the other stuff(whatever that may be) in the file.

I'd also like to learn how to find certain text in a file, then based on where that is, place some data after the text that was found...I hope I explained that well.

So if someone could lead me in the right direction, I'd really appreciate it. I've learned to do the following code from a book, but it didn't teach me how to do either of the things above...And I am trying to think of a way to do it, but can't come up with one. Nor has google helped(might just be searching for the wrong sorta thing).

Code:

#include <stdio.h>

int main (int argc, const char * argv[]) {
	FILE *filePtr; 
	char fileContents; 
	char c;
	
	c = 'a';
	
	filePtr = fopen("../../test.txt", "r"); 
	
	if(filePtr == NULL) 	{
		printf("Error opening file.");
	}
	else 
	{
		while((fileContents = fgetc(filePtr)) != EOF) 
		{
			putchar(fileContents); 
			
		}
		fclose(filePtr); 
	}
	
	filePtr = fopen("../../test.txt", "w");
	
	if(filePtr == NULL)
	{
		printf("Error opening file, to write to it.");
	}
	else 
	{
		fputc(c, filePtr);
	}

	
    return 0;
}

[leeor_net]

Change filePtr = fopen("../../test.txt", "w"); to filePtr = fopen("../../test.txt", "a"); for 'append' mode.

Remember, Google is your friend.

[SamGray]

Change filePtr = fopen("../../test.txt", "w"); to filePtr = fopen("../../test.txt", "a"); for 'append' mode.

Remember, Google is your friend.

Thank you, I had actually just found that in my book when I saw your post. I somehow missed that part.